This invention relates to an improved diverter valve of the type disclosed in the Perry et al U.S. Pat. No. 4,036,249, issued July 19, 1977, in which the valve body and associated parts are cast from urethane, a material admirably suited to withstand the severe conditions imposed upon equipment used in septic field installations.
Septic systems, used extensively to treat sewage in areas not served by public sewage systems, normally comprise a septic tank in which the raw sewage is collected and most of the solids separated from the liquid components. The solids are largely decomposed by anerobic bacteria within the tank, the residual solids settling to the bottom while the liquid effluent is discharged into a drain field and absorbed in the soil. The effluent, however, contains a certain amount of suspended solids and organic matter, and over a period of years, these materials tend to clog the drain field and materially reduce its efficiency. Thus, the most vulnerable segment of systems of this type is the drain field. In septic systems in which only a single leg or line of drain tile is employed, in time, the clogging action may reduce the efficiency of the field to such an extent as to require an extension of the original field or the installation of a new field.
During the past decade it has been demonstrated that if a drain field is permitted to "rest" at periodic intervals, its efficiency will be largely restored. It follows that if a drain field comprising at least two rather than a single leg or line of drain tile, by using a suitable valve arrangement, the legs or lines of the drain field may be used alternatively, permitting one leg to "rest" while the other leg is in operation.
The cast urethane valve described in the Perry et al patent, identified above, is particularly adapted to be used for this purpose in view of its rugged, simple construction and resistance to deterioration, thereby assuring continuous trouble-free operation with minimum maintenance expense.
The casting of a valve of the type disclosed in said patent, however, does involve a relatively expensive manfacturing operation and its design does not lend itself to a less expensive injection molding operation.
One of the objects of the present invention is to provide a diverter valve of novel design incorporating all of the advantages of the cast urethane valve, including resistance to all forms of deterioration, but one that may be injection molded from PVC or ABS plastic, at a considerable savings in manufacturing costs.
A further object of the present invention is to provide a sealed valve that may be used in septic tank systems operating under positive as well as normal pressures. The introduction of water under pressure in systems of this type has been found to enhance the distribution of effluent in the drain field, improves aerobic digestion, and results in a more rapid decomposition of the waste components of the effluent.